Semi-rigid airfoil for airborne vehicles

ABSTRACT

The present invention relates to a semi-rigid airfoil for use with airborne vehicles and capable of being folded and/or warped. The airfoil includes a rigid spar defining a leading edge and a cable defining the trailing edge with the root end thereof secured to the fuselage of the vehicle and the other end to a tip truss structure, with a flexible material forming top and bottom airfoil surfaces. Means are also provided for twisting portions of the airfoil about an axis extending through the root end, and means for pivoting the spar to fold against the fuselage.

United States Patent 1191 Sweeney et al. July 3, 1973 [54] SEMI-RIGIDAIRFOIL AIRBORNE 3,273,828 9/1966 James 24l43 vgmcms 3,614,032 10/1971Purcell, 11.... 244/36 3,446,458 5/[969 Rogallo 244/93 1 Inventors: T m:E- S een y, mce on. J 3,197,158 7/1965 Rogallo.... 244/49 Philip M.Condlt, Mercer island, 3,194,514 7/1965 Rogallo 244/49 Wash; Robert A.Ormiston, m 3 Walter Barry Primary Examiner-Milton Buchler remonAssistant Examiner-Carl A. Rutledge [73] Assignee: Thomas E. Sweeney,Princeton, NJ. Attorney-Michael York [22] Filed! May 19, 1971 21 Appl.No; 144,861 [571 ABSTRACT Related Application Data The present inventionrelates to a semi-rigid airfoil for use with airborne vehicles andcapable of being folded [62] June 1968 and/or warped. The airfoilincludes a rigid spar defining a leading edge and a cable defining thetrailing edge 52] Cl. 244/36 244/49 244/7 C with the root end thereofsecured to the fuselage of the [51] Int. Cl. 1/00 B64c 3/56 vehicle andthe other end to a tip truss structure, with 5 Field 5 3 5 a flexiblematerial forming top and bottom airfoil sur- 244/49 3 5 faces. Means arealso provided for twisting portions of the airfoil about an axisextending through the root 56} Reterences Cited end, and means forpivoting the spar to fold against the UNITED STATES PATENTS fuselage3,599,904 8/1971 Condit et a1. 244/46 5 Claims, 11 Drawing FlguresvPatented July 3, 1973 4 Sheets-Sheet 1 Patented July 3, 1973 4SheetsSheet 3 FIG. 5

FIG.

Patented July 3, 1973 4 Sheets-Sheet 5 FIG.7

Patented July 3, 1973 4 Sheets-Sheet 4 FIG. 8

FIG. H

SEMI-RIGID AIRFOIL FOR AIRBORNE VEHICLES This application is a divisionof parent application, Ser. No. 740,895, filed June 28, 1968, now U. S.Pat. No. 3,599,904.

This invention relates to semi-rigid airfoils, or sailwings, and moreparticularly to apparatus for warping and/or folding semi-rigidairfoils.

The use of airfoils of semi-rigid construction in which a rigid sparsupports a flexible wing form dates back to the earliest successesenjoyed by the pioneers of flight. The predominant use of rigid wingedaircraft in present commercial flights is well known. Ailerons presentlyperform functions, such as roll control, which were accomplished bywarping or twisting of the former flexible wings in order to createunequal or opposing lifting forces on opposite sides of the aircraft.

Rigid wings presently known to the art are considerably more expensiveto fabricate than semi-rigid or flexible winged aircraft. Costs ofmaterials are necessarily passed on to the purchaser of such craft,which in many cases may be one of the growing numbers of persons who owna small plane for pleasure or business.

Known aircraft having a high aspect ratio, such as gliders, have rigidwings which must be disassembled such that the aircraft can betransported between the place of storage and the airport. Suchdisassembly includes detaching the wing from the fuselage, this in mostcases requiring the work of at least two persons. Considerable time isconsumed and often tools are required to perform the operation.

It is an object of the present inventionto provide a semi-rigid airfoilof the sailwing type which is foldable and capable of being warped atwill in predetermined magnitudes.

Another object of the present invention is to provide a warpingapparatus for a semi-rigid airfoil of the sailwing type.

A further object of the present invention is to provide a semi-rigidairfoil of the sailwing type for use with and as an extension of a fixedand rigid airfoil, the semirigid airfoil being foldable such that theleading edge thereof forms the wing tip fairing of the fixed rigid wingwhen in a folded position.

A yet further object of this invention is to provide a semi-rigidairfoil of the sailwing type for use with-fixed wings as above,including apparatus for warping the form of the semi-rigid airfoil.

Another object of this invention is to provide a folding semi-rigidairfoil of the sailwing type for use with a helicopter wherein thesemi-rigid airfoil provides means for increasing high-speed performanceof the helicopter by substantially unloading the rotor of the helicopterduring forward motion of the craft.

A yet further object of the present invention is to provide a semi-rigidairfoil of the sailwing type for use with a helicopter or-other verticaltake-off and landing aircraft wherein such airfoil includes means forwarping or twisting the form thereof.

Another object of the present invention is to provide a foldingsemi-rigid airfoil of the sailwing type in combination with a liftingbody or a spent rocket booster or missile, the folding airfoil providingmeans for maintaining a relatively shallow glide angle of the liftingbody.

The present invention fulfills the aforementioned objects and overcomeslimitations and disadvantages of prior art solutions to existingproblems by providing a flexible semi-rigid airfoil of the sailwing typewhich may be folded and/or warped, and further providing specificapplications or uses of the sailwing. These applications include the useof the foldable and warpable sailwing structurally combined with rigidwings of a fixed-wing aircraft; a helicopter; a lifting body or amissile or rocket booster; or other aerodynamic structures.

The airfoil, in a preferred embodiment, includes a hinged rigid spardefining the leading edge of the sailwing. A cable extending between aroot point and the extremity of the airfoil defines the trailing edge ofthe sailwing. Warping means for twisting portions of the airfoil aboutan axis extending through the root point includes a truss hingedlysecured to the spar for pivotal movement about the hinge axis extendingthrough the root point. A control stick for use by the pilot of thecraft is interconnected with the truss by a plurality of cables andpulleys responsive to movement of the con-.

trol stick. Thus movement of the control stick causes the truss to pivotabout the hinge axis, thereby changing the lifting forces on theairfoil. The pivoting of the truss according to the present invention isaccomplished with substantially no change in the trailing edge cabletension throughout the angular range of the warp, this resulting inminimal control forces being required to produce the warp.

In embodiments of the present invention wherein the semi-rigid airfoilis structurally combined with fixed rigid wings of an aircraft, theaspect ratio of the wing is considerably increased with a relativelysmall addition of weight. A retractable wing tip comprising an airfoilof the sailwing type is hingedly mounted to a conventional hard wing.The spar of the sailwing forms a wing tip fairing when retracted.

In embodiments of the present invention wherein a folding semi-rigidairfoil of the sailwing type is structurally combined with a helicopteror other vertical takeoff and landing vehicles, high forward speedperformance of the craft is substantially increased by the unfolding ordeployment of a foldable sailwing once the craft is lifted to thedesired altitude and forward speed is experienced. The sailwing ismaintained in the folded or retracted position during lift-off in orderto eliminate high downloads which would be produced if the airfoil werein the rotor downwash. Similarly, the semi-rigid airfoil can beretracted in order to avoid aerodynamic blockage to the rotor system inautorotational descent.

The embodiments of the present invention employing a foldable andwarpable sailwing in structural combination with a lifting body or amissile or rocket booster, include means for enabling a shallow glideand lower speed landing of such lifting bodies after reentry fromextraplanetary spatial vacuum into the atmosphere. The sailwing isfolded in a stowed condition within the lifting body until reentry ofthe lifting body'into the atmosphere, whereupon the sailwings aredeployed. Deployment is accomplished, in one embodiment of the presentinvention, by means of solid propellant rockets disposed at the tips ofthe semi-rigid airfoils which, in a preferred embodiment of theinvention, will be interconnected to prevent the deployment of oneairfoil without the other, and to further cause both airfoils of anaircraft to be deployed simultaneously. The trust of the rockets carryeach airfoil from a stowed position to an unfolded or fully operableposition. It is within the scope of the present invention to includemeans for controlling the descent of the lifting body through theatmosphere such that a precise descent pattern or flight path may bepredetermined.

The invention will be more clearly understood from the followingdescription of specific embodiments of the invention together with theaccompanying drawings, wherein similar reference characters denotesimilar elements throughout the several views, and in which:

FIG. 1 is a fragmentary schematic plan view of wing warping apparatusaccording to the present invention;

FIG. 2 is an enlarged fragmentary sectional plan view of a tip portionof the wing of FIG. 1;

FIG. 3 is a schematic end view of the wing tip shown in FIG. 2, lookingalong lines 3-3 of FIG. 2;

FIG. 4 is a fragmentary schematic perspective view of a warping controlsystem according to the present invention;

FIG. 5 is a top plan view of an aircraft employing sailwing type tipsaccording to the present invention with the tips shown in a retractedposition;

FIG. 6 is a top plan view of the aircraft shown in FIG. 5 wherein thesailwing tips are in a deployed position;

FIG. 7 is a top plan view of a helicopter equipped with foldable andwarpable sailwings according to the present invention;

FIG. 8 is an elevational view of the helicopter shown in FIG. 7 in whichthe sailwings are deployed;

FIG. 9 is an elevational view of a rocket equipped with foldingsailwings according to the present inventron;

FIG. 10 is a perspective view of the rocket shown in FIG. 9 in which thesailwings are deployed; and

FIG. 11 is a perspective view of a lifting body in the form of anextraplanetary vehicle equipped with folding sailwings according to thepresent invention.

FIGS. 1 and 2 show a semi-rigid flexible airfoil of the sailwing type.For purposes of illustration, the preferred embodiment of the sailwingairfoil shown in FIG. 1 is described as a wing 10 for an airborne bodysuch as an aircraft.

The wing assembly 10 shown in FIG. 1 includes a rigid spar 13 which ishinged at point 11 to fuselage 12 of the vehicle with which wing 10 isto be used. Rigid spar 13 defines the leading edge of the airfoil 10 andis hollow in the preferred embodiment shown in FIG. 1. The material ofspar 13 may be wood, metal or other suitable material. Atriangular-shaped truss assembly 14 is secured on its base leg 20 forpivotal movement about a hinge axis 15 near the end of spar 13 by a pairof support struts 16 and 17. Support struts 16 and 17 are formed withbearing portions 18 and 19 respectively, at one end of each. Theopposite ends of these struts are secured, such as by welding, to spar13.

Truss assembly 14 is formed in a triangular shape, although any suitablepolygonal configuration is within the scope of the present invention.The base, or first, leg 20 of the truss assembly is disposed coaxiallywith respect to hinge axis 15 and is journaled within bearing portions18 and 19 of support struts 16 and 17, respectively. The second andthird legs 21 and 22 of the truss 14 extend from opposite ends of firstleg 20 and terminate in a tip portion 23. A wing tip 54 is secured alongone of its edges to the leg 22 of the truss and therefore moves with thetruss as it pivots within the bearings 13 and 19.

A cable 24 has one end secured to the tip 23 of the truss 14 and itsother end to a root point 25 on the fuselage 12. Cable 24 defines thetrailing edge of airfoil 10. A piece of flexible material 26 extendsfrom a first edge forwardly around the spar 14 without attachmentthereto so as to allow wing warping and thence back to its first edgewhere it is seamed. The seam constitutes the trailing edge of theflexible material and is formed in the shape of a catenary are forproviding chordwise tension in a direction parallel to the centrallongitudinal axis of the aircraft supporting the airfoil. The seam issecured to cable 24, such as by providing eyelets or lacing secured tothe seam through which cable 24 is passed. Material 26 is preferablymade of dacron sailcloth impregnated with silicon, but may also becanvas, plastic or other suitable flexible material and it defines theshape of the airfoil. The tension in wing material 26 is controlled byvarying the tension in cable 24.

As shown in FIG. 1, the hinge axis 15 for the truss 14 extends coaxiallywith respect to the base leg 20 and thereafter through the fuselage rootpoint 25. A catenary defined by cable 24 extends from truss tip portion23 tangentially with respect to and terminating at root point 25. Thus,pivoting or rotation of truss assembly 14 about its hinge axis 15results in constant tension in cable 24 since' the distance between thetip 23 and root point 25 remains constant during all angles of warp. Itis the maintenance of constant tensile stresses in cable 24 whichminimizes control forces. This is described below.

As seen best in FIGS. 2 and 4, horn member 27, having an upper end 28and a lower end 29 is rigidly secured, such as by welding, to anextension of the truss base leg 20. The portion of the horn between thebase leg 20 and each of its ends 28 and 29 defines a lever arm whichgives rise to a mechanical advantage when forces are exerted on eitherof these ends to effect pivoting of truss assembly 14 about hinge axis15. Of course the length of this lever arm may be of different lengths.

FIG. 4 shows a preferred mechanism for controlling the magnitude ofpivotal movement of truss assembly 14, and thus the warping of wingassembly 10. The control mechanism 30 includes a control stick 31,having a handle 32 at one end and a hub 33 at the other end. The hub 33is journalled into a support member 34 which can be a fixed supportingmember on the aircraft, so that the elevation of the hub is fixed. Thecontrol stick can be moved around support 34 from left to right.Alternatively, the control stick 31 may be fixed to support member 34with remote portions of member 34 being journalled in bearings.

A pair of arms 35 and 53 .are fixed to hub 33 and extend radially fromthe hub and coaxially with respect to each other. Control cables 36 and37 are secured to arms 35 and 53 respectively, and extend around pulleys38 and 39. The cable 36 passes around pulleys 38 and 40 to an arm 42which is fastened to a hub 44. Similarly, cable 37 passes around pulleys39 and 41 to an arm 43 on the hub 44. Arms 42 and 43 are secured to andextend radially from hub 44 which, in turn, is fixedly secured to asupport rod 45 which is mounted on the vehicle body.

A second pair of arms 46 and 47 are also secured to hub 44 and extendradially therefrom and coaxially with respect to each other. The axes ofarms 42, 43 and 46, 47 are preferably prependicular with respect to eachother.

A second pair of control cables 48 and 49 are secured to arms 46 and 47,respectively. This pair of cables extends through spar 13, aroundpulleys 50 and 51, respectively, which are also located within the spar.The ends of the cables 48 and 49 are secured to the upper and lower endsof 28 and 29 of the horn member 27. Pulleys 50 and 51 are mounted forrotation to a support bar 52, which is secured to spar l3 and located inthe spar interior.

FIG. 4 is a fragmentary view of the control system and shows only onecable arrangement for controlling one wing airfoil. Extensions 48A and49A of cables 48 and 49, respectively, are also shown broken off ordiscontinued. It should be understood that a symmetrical or mirror imageof the above-described puliey and horn member arrangement exists for anairfoil (not shown) on the opposite side of the aircraft. Cable 48 andextension 48A, while shown coaxially with respect to each other, areeach secured to arm 46. Similarly, cable 49 and extension 49A are eachsecured to arm 47. Thus, pivoting of hub 44 by manipulation of controlstick 31 will cause opposite movement of the horn members on oppositesides of the vehicle. This necessarily results with the structure ofFIG. 4 because increases in tension in either of cables 48 or 49 resultsin decreases in tension or slackening in their counterparts 48A or 49A.

In operation of the bridle control system of FIG. 4, the pilot movescontrol stick 31 either to the right or left (R or L in FIG. 4) toeffect warping. As an example, movement of control stick 31 to the rightlifts arm 35 or hub 33 which results in increasing tension in controlcable 36. This causes a downward pivotal movement of arm 42 on hub 44about the axis of support rod 45. The resulting pivoting of hub 44causes an increase in tension in control cable 48, thereby moving upperend 28 of horn member 27 toward pulley 50. Movement of horn member 27 inthis direction results in pivoting of truss assembly 14 upward with anassociated warping of the form of wing assembly 10. In a like manner,movement of the control stick 31 to the left produces tension in cable37 which acts to move arm 43 of hub 44 down, thereby applying tension tocable 49 and moving the truss l4 downward.

FIG. 3 shows several airfoil configurations which can be achieved bymovement of the control system and subsequent operation of the warpingcontrol. Reference numeral 23a represents the location of truss tip 23of the truss when in an unwarped, or neutral, position. Upon movement ofcontrol stick 31 to the right as described above, truss tip 23 ispivoted upward, for example to the position designated 23b in FIG. 3.Movement of control stick 31 to the left moves truss tip 23 down, forexample to the position shown in 230. For the case where truss tipportion 23 is moved to the position designate 230 from position 23a, anincrease in the angle of attack is achieved, resulting in a tendency ofthe airfoil to lift. For the case where truss tip portion 23 is moved tothe position designated 23b from position lected magnitudes of warp. Itis also obvious from FIG.

3 that the distance between any of points 23a or 2312 or 23c and rootpoint 25 remains substantially constant throughout the warpingoperation, since the locus of points defined by tip 23 during itsmovement is a curve of substantially constant radius.

In the preferred embodiment of the control structure shown in FIG. 4,upward movement of tip portion 23 in one wing will necessarily result indownward movement of the tip portion of the aircrafts opposite wing,since increases in tension in control cable 48, for example, will beaccompanied by decreases in tension in its counterpart. It is alsopossible to include individual controlling of warping for each airfoil(wing) or sailwing when two or more are used.

Deployment of wing assembly 10 from a folded to an unfolded position,the latter position illustrated in FIG. 1, is accomplished by ahydraulic cylinder assembly 5 which includes a cylinder 6 and a push rod7. The cylinder is secured to the fuselage 12 and the rod is secured tospar 13 at point 8 such that its reciprocating movement moves the wingassembly 10. Thus, on rod 7 retracting into cylinder 6, wing assembly 10is folded in a pivoting motion about hinge point 11 in toward thefuselage. In the deployed position shown in FIG. 1, hydraulic pressuremaintains rod 7 in an unyielding and rigid manner against loads uponwing assembly 10 tending to cause pivotal movement of the assembly aboutpoint 11. The control circuit for the cylinder assembly 5 is not shown,but it can be of any suitable conventional construction. It is withinthe scope of the present invention to include other means for deployingfolding wing assemblies, such as over-center-lock linkage.

FIGS. 5 and 6 show retractable sailwing airfoil tips used in combinationwith conventional hard wings of an aircraft. This arrangement permitsthe wing area and aspect ratio to be altered in flight by an amountcorresponding to the area occupied by the sailwing tips. It is intendedthat the airfoil and control means desscribed above for FIGS. l-4 becharacteristic of the sailwing tips described in FIGS. 5 and 6, and theother applications described below in FIGS. 7-11.

In FIGS. 5 and 6 an aircraft 60 includes a conventional fuselage portion61, tail portion 62 and two hard wings 63 with ailerons 63a.Sailwing-type tip assemblies 64 and 65 are hingedly secured to each ofthe wings 63 at points 66 and 67.

Sailtip assemblies 64 and 65 are similar in structure to the wingassembly 10 of FIGS. 14 already described. Only tip 64 is describedsince the other tip 65 is similar. A rigid spar 68 (FIG. 6) defines theleading edge of either of the tips 65 or 64, and a trailing edge cable69 defines the trailing edge. In the retracted position shown in FIG. 5,spar 68 becomes the wing tip fairing of wing 63. By deploying thesailwing tip assemblies 64 and 65, the aspect ratio and wing area areincreased, providing both a lower wing loading and increased induceddrag efficiencies. The term aspect ratio, as used herein, is the ratioof wing span to the mean chord dimension of the wing.

The sailtip assemblies 64 and 65 can be deployed by the hydraulic pistonand cylinder arrangement disclosed for wing assembly 10. During flightat relatively high speeds, the pilot of the aircraft 60 will maintainthe sailtip assemblies 64 and 65 in a retracted position, as shown inFIG. 5. With the tips retracted, the requirements of low aspect ratio atsuch high speeds is met. At lower flight speeds, the sailtip assemblies64 and 65 are deployed thereby increasing the aspect ratio and wing area(See FIG. 6). Using the present invention, induced drag reductions of upto 40 percent are possible for landings with low aspect ratios sinceflight with the sailtip assemblies extended will result in an increasedaspect ratio with a resulting decrease in airflow downwash angle. Thusthe drag caused by lift and induced by the downwash resulting from thislift will also decrease. The increased wing area provides lower stallspeeds for landing of the aircraft.

The semi-rigid airfoil, or sailwing, according to this invention canalso be used as an auxiliary wing for a helicopter. It is known that thecruise and high speed performance of a helicopter can be substantiallyincreased by the addition of a relatively small wing to the craft. Thefunction of the semi-rigid wing in this case is to substantially unloadthe rotor, thereby permitting more efficient use of availablehorsepower, and to provide an airfoil capable of being folded out of thedownwash of the rotor.

FIGS. 7 and 8 show a helicopter 70 with the conventional fuselage 71 androtor 72. Helicopter 70 is equipped with two semi-ridig airfoil orsailwing assemblies 73 and 74, each assembly capable of folding back outof the downwash of the rotor. The folded position is illustrated forsailwing assembly 74, while a fully deployed or unfolded position isillustrated for assembly 73 in FIG. 7. The deployed position of assembly74 is shown by the dotted lines of FIG. 7. Sailwing assemblies 73 and 74each pivot about hinge point 75. Each of sailwing assemblies 73 and 74is structurally similar to wing assembly described for FIG. 1 above. Arigid forward spar 76 defines leading edge 77. Trailing edge cable 78defines the trailing edge of assembly 73. Flexible material 79 coversspar 76 and is secured to cable 78 to form the airfoil surface. A trussassembly 80 functions in much the same manner as truss assembly 14described for FIG. 1 where warping of sailwing assembly 73 is desired.

Folding and unfolding of the auxiliary wing assemblies 73 and 74 areaccomplished by a hydraulic cylinder assembly (not shown) or othersuitable means. The relative easy foldability of assemblies 73 and 74facilitates storage in a relatively small space in the fuselage, theflexible material 79 folding in an accordian-like fashion.

In operation, sailwing assemblies 73 and 74 are retracted for low speedand hovering flight regime and also for autorotational descent. Forcuising and high speed flight, the sailwing assemblies are deployed fromtheir folded position. In a preferred form of the invention the sailwingassemblies are preferably made capable of being folded flush with thesides of the fuselage by providing receptacle wells in the sides of thefuselage. FIG. 8 also illustrates the appearance of helicopter 70 withsailwing assemblies 73 and 74 fully deployed.

The semi-rigid airfoil or sailwing of the present invention also can beused to allow recovery of and controlling the post-reentrycharacteristics of spent rocket booster payloads, such as the type usedin known defense or aerospace missions. FIG. 9 shows a booster 82equipped with sailwings 83 and 84 folded along and into the sides of thebooster main structure, as would be the case prior to or during launch.The spars of the sailwings are shown in FIG. 9. Hinged tips 85 and 86which form the wingtip fairing for sailwings 83 and 84, respectively,similary fold along sides of the booster. An inflatable nose fairing 87permits mating of the nose of the booster with its payload withoutinterference.

Solid propellent rockets 88 are secured to each tip of sailwings 83 and84 or other suitable linkage to provide the forces necessary to deploysailwings 83 and 84 from the folded position shown in FIG. 9 to thefully deployed position shown in FIG. 10, deployment including apivoting of the sailwing assemblies about hinge points 89. The thrustinitiation of the rocket is either pre-programmed or controlled bysignals from a remote location.

In operation, after burnout, the sailwing assemblies 83 and 84 aredeployed by the rockets 88 and the nose fairing 87 would beautomatically inflated, thereby transforming the separated booster intoa glider whose flight path and landing area is capable of control byconventional electro-mechanical remote control devices operated from aground installation, for exmaple. The inflatable nose fairing 87 reducesfuselage drag of the craft. The relatively expensive booster can berecovered without damage, facilitating its possible re-use.

FIG. 11 shows an extraplanetary reentry vehicle or lifting body 90having a shape determined by thermodynamic, hypersonic, supersonic andsubsonic aerodynamic parameters. Lifting body 90 provides an astronautwith a vehicle capable of making controlled glidetype landings on terrafirma rather than parachuting into the sea. A transparent bubble 91provides means through which the astronaut may see to determine whetherchanges in flight path are necessary. Fins 92 aid in stabilizing thecraft during its descent.

Folding sailwing assemblies 93 and 94 of the type previously describedfor FIG. 1 are hinged about hinge points 95 such that each sailwing willretractably fit into a slot in the sides of the lifting body. A majoradvantage of the use of such semi-rigid airfoils or sailwings is thefact that the shape of lifting body 90, as determined by the aboveparameters, may be retained for all flight regimes other thanmerely thesubsonic glide phase. In this latter regime the sailwings are deployedin flight, thereby permitting flight characteristics approaching thoseof a conventional airplane, with associated favorable handlingqualities.

The embodiments of the invention particularly disclosed are presentedmerely as examples of the invention. Other embodiments, forms ormodifications of the invention coming within the proper scope of theappended claims will of course readilysuggest themselves to thoseskilled in the art.

What is claimed is:

1. Aircraft apparatus, comprising a lifting body, an airfoil supportedby the body including a rigid leading edge, a cable defining a trailingedge, and flexible material engaging said leading edge and extending forthe entire distance between said leading edge and the cable for definingportions of the form of the airfoil; said cable being secured at a rootend thereof to the body at a predetermined point, means including saidcable for varying the warp of the airfoil, and means for moving saidairfoil from a first retracted position to a second postion wherein saidairfoil is deployed.

2. Aircraft apparatus according to claim 1, wherein said lifting bodyhas a slot for receiving at least a por- 3 ,743 ,21 8 9 10 tion of saidairfoil when said airfoil is in the first recomprising at least one finextending upward from the tracteq Position aft portion of said liftingbody.

Alrcraft apparatlls whefem 5. Aircraft apparatus according to claim 1,further said means for moving said airfoil includes a hinge point onSaid lifting body about which Said airfoil is comprising a transparentbubble located on said lifting hinged. body.

4. Aircraft apparatus according to claim 1, further

1. Aircraft apparatus, comprising a lifting body, an airfoil supported by the body including a rigid leading edge, a cable defining a trailing edge, and flexible material engaging said leading edge and extending for the entire distance between said leading edge and the cable for defining portions of the form of the airfoil; said cable being secured at a root end thereof to the body at a predetermined point, means including said cable for varying the warp of the airfoil, and means for moving said airfoil from a first retracted position to a second position wherein said airfoil is deployed.
 2. Aircraft apparatus according to claim 1, wherein said lifting body has a slot for receiving at least a portion of said airfoil when said airfoil is in the first retracted position.
 3. Aircraft apparatus according to claim 1, wherein said means for moving said airfoil includes a hinge point on said lifting body about which said airfoil is hinged.
 4. Aircraft apparatus according to claim 1, further comprising at least one fin extending upward from the aft portion of said lifting body.
 5. Aircraft apparatus according to claim 1, further comprising a transparent bubble located on said lifting body. 